Careless error, help diagnosing after frying it?

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KO4NDP
 

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Joined: 25 Jul 2022, 19:15

Careless error, help diagnosing after frying it?

Post by KO4NDP »

Kudos to DL2MAN and PE1NNZ for designing and implementing such an awesome project. And Malahit for the kit they sold which I had zero problems with so far. Hooked it up to an existing antenna and a PS via a new cable, and turned on and worked first try. (though haven't pushed ptt yet)

But I did something careless when in a rush to get it on battery. I mis-wired a new cable to attach it to a battery holder, didn't notice until it was too late, after I'd put reverse polarity to it. :oops: Immediately it gave an audible pop along with the magic smoke. I promptly unplugged it.

Re-did my cable, and figured what the heck - if it's fried, it's fried, and plugging it in can't hurt it anymore than it already is. So I did, and it powered up. Tuned around, there's CW and SSB, display works, speaker and headphone jack works, buttons work (still haven't checked ptt but I'm betting it's fine). I'm amazed. Can't find anything that doesn't work (short of pushing ptt)

Unplugged it and disassembled case and inspected the boards. You know when you see something fried, but nothing *looks* fried, traces look ok, bits look ok, though a couple caps' housing coating are "flaky" but seem working. But you don't have a pop like I heard without something awry.

DL2MAN, and anyone who knows the design intimately, is there anything specific you recommend I test to check for failure or future failure? Is there reverse polarity circuitry and a diode may have just given up its one life and doesn't have another to give? Those flaky caps near power input that I may want to test, and possibly just replace regardless if they're working? Etc, anything?

Thanks in advance
Jason KO4NDP
AC9YY
 

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Location: Illinois, USA

Re: Careless error, help diagnosing after frying it?

Post by AC9YY »

Check C2 and C4 on the mainboard at a minimum.
DL2MAN
 

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Re: Careless error, help diagnosing after frying it?

Post by DL2MAN »

My best guess would be C2, C4 and C8.
I´m feeling with you. But you´re a very lucky man...
Normally we would discuss now all the IC´s that need to be changed.
You should consider to go buy a lottery ticket ;)

73 Manuel; DL2MAN
N4XTL
 

Posts: 24
Joined: 08 Jul 2022, 01:44

Re: Careless error, help diagnosing after frying it?

Post by N4XTL »

C2 is likely what you heard and smelled. Tantalums do not like reverse voltage and it is directly across the +12V input. It's possible that it failed short circuit briefly and collapsed the 12V input, protecting everything downstream in a way. Thankfully it doesn't sound like it caught on fire, which tantalums do. :D

Even though the digital stuff is working, still check the 5V rail to make sure the 78L05 is regulating properly. I would have expected that to be damaged. C4 should be checked and probably replaced to be safe, just like C2.

On the RF board, the INA219 takes +12V so you should make sure your onboard power measurements are functional. The FETs should be fine but you'll once again verify that by transmitting into a dummy load and checking output power and measurements.
KO4NDP
 

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Joined: 25 Jul 2022, 19:15

Re: Careless error, help diagnosing after frying it?

Post by KO4NDP »

Thanks everybody. Based on your recommendations I'm looking at C2, C4, and C8 specifically, at a minimum.

C2 is absolutely blown. As obvious as it looks here, it wasn't as obvious until I got a photo of it, zoomed in. C4 does not look malfunctioned, but might be worth replacing anyway if it's of the same specs as C2. I'm still looking for the C8 waldo.
https://drive.google.com/file/d/18JVa9R ... sp=sharing

There's another bad fault though, C41 (also 10uF/25V), in the USB circuit
https://drive.google.com/file/d/1zD1_Le ... sp=sharing

I just connected to a power supply, and PTTd into a dummy load. It's showing 0.0W and not giving an efficiency reading, showing nan% which makes sense dividing by 0w, but not good. This I'm guessing is more likely the INA219 as N4XTL described, and not just one of those 2 blown caps?

Connected usb to a computer, win11. Laptop didn't like it, said usb power surge and that the device is consuming more power than is available. That is likely coming from the C41 issue. But as N4XTL said there could also be an issue with the 78L05 at U2.

I've not bought surface mount components before, for caps just thru hole electrolytic and ceramic. For the tantalums, can you confirm these 10uF: https://www.digikey.com/en/products/det ... 90/5001381
I don't see (C8) 470uF tantalum at digikey or mouser, is that supposed to be tantalum?
Any chance there's a recommended parts pick list or similar that I haven't come across?
Lol am I better off at this point tossing this and getting another kit? I don't mind putting money and time into it, I own my mistakes. But of course there's a line.

Thanks
Jason KO4NDP
KO4NDP
 

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Joined: 25 Jul 2022, 19:15

Re: Careless error, help diagnosing after frying it?

Post by KO4NDP »

And regarding my question about a part list, I found what I was looking for in the group buy instructions.
https://dl2man.de/1-trusdx-group-buy/
I'll have to play with this as I'm inexperienced with, well, all of it really. Specifically pcb design files and uploading them to manufacturers and such. But now it's become an interesting project by itself.

Edit: Just went through the parts list spreadsheet, and looked up all the parts in LCSC. Added the needed caps (a few 470uf tantalums, a few 10uf tantalums, and 50 or 100 minimum each of a bunch of the other ceramic caps, just in case), 1n4148 diodes, and the ICs mentioned (INA219, L8L05). All told it'll be about $6usd, with another few bucks in shipping, so for about $15 hopefully it'll get fixed and I'll have several hundred doodads left over, and if anyone local has an issue and needs something I'll be glad to pass them on.

Transistors are not available so with any luck they're ok.

Wish me luck
Thanks again
Jason KO4NDP
N4XTL
 

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Re: Careless error, help diagnosing after frying it?

Post by N4XTL »

The 5V USB rail (VBUS) is provided by the computer that you plug in to, not the 78L05. VBUS is connected to the +12V input through a diode D3, so that the radio can be powered off of VBUS or 12V, but not both. Unfortunately this means that D3 turned on with the reverse polarity 12V, so it makes perfect sense that C41 blew. It also means that the CH340G USB chip could be fried. If you haven't ordered yet you might want to throw one of those in the cart.

The ATmega328P connects to a few pins on the CH340G, but there's no way to know if those pins were damaged until you replace C41 and maybe the CH340G and try connecting it to the computer again. It's a good sign that most of your digital stuff seems to be working normally.
KO4NDP
 

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Re: Careless error, help diagnosing after frying it?

Post by KO4NDP »

Thanks, I'll do that. I haven't placed an order yet, trying to cross reference components in mouser, digikey, and other local sources for a little quicker delivery. Most of it is in stock local, but the expected bits aren't. But it's looking like I might have to bite the bullet for at least some of it to come from lscs who seem to have more of it all than anyone else.

Really appreciate your help in diagnosing this and thinking through it. It's going to be an interesting story when it's all back together working as intended.

Jason KO4NDP
AntonR
 

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Joined: 23 May 2022, 10:44

Re: Careless error, help diagnosing after frying it?

Post by AntonR »

Hi Jason,

You are not the only one. Had fireworks tonight because of a stupid 12V polarity switch.

I’m on vacation right now but will follow your progress and when I’m home I’ll give it a try.

This thread gives me some hope after my mistake!

Pro tip: Beer and electronics are not a good combination 😬

73, Anton PD5ANT
DO1OKE
 

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Re: Careless error, help diagnosing after frying it?

Post by DO1OKE »

The same "happened" to me while on vacation. It was C2 and the BS170's that were blown. So no worries ;)
DO1OKE
 

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Re: Careless error, help diagnosing after frying it?

Post by DO1OKE »

AntonR wrote: 27 Jul 2022, 20:58
Pro tip: Beer and electronics are not a good combination 😬

73, Anton PD5ANT
I can second that :lol:
KO4NDP
 

Posts: 10
Joined: 25 Jul 2022, 19:15

Re: Careless error, help diagnosing after frying it?

Post by KO4NDP »

Since more folks are following (!!! :) ), I ordered some bits and boops from digikey a couple days ago, will be arriving tomorrow.

I was able to get replacements for:
-The tantalum caps which are the most obvious items needing replacement since they're toast (at least the two 10uFs). A few too many of each 10uF and 470uF, just in case I do something stupid which is assured.

Now I could have stopped there, but I didn't want to replace those and find something else that just cost a few cents more to begin with but have to pay another several dollars in shipping and wait several days. So I also got "probable" failure replacements too:
- The 78L05
- I could not get a CH340G directly, so instead I got a sparkfun breakout board that has one on it, desolder from the breakout board and put on the trusdx power board. It _looks_ like the same IC package, I'll know when I get it. I'll only use it if I find that it needs replacing, otherwise it'll go in the drawer.

As N4XTL also pointed out, and I verified, power is not being measured properly. That could be from all of the above, but might also be the INA219. I could not get that from digikey or mouser or adafruit, not even in a breakout board it seems? So I got a cheap INA219 breakout board off amazon. It for sure is the wrong IC package, BUT it should be deadbuggable, datasheet indicates the pins are 100% flipped. I'll confirm and do that if I've done everything else above and still don't have a power reading.

I'll follow back up later in the weekend after I've gotten it all and had time to do stuff.
I hate it for you guys but glad I'm not in the boat alone!
Jason KO4NDP
W3SI
 

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Location: Edgewater, FL

Re: Careless error, help diagnosing after frying it?

Post by W3SI »

You are not alone in the power troubledhooting... while attempting to adjust coils for better efficiency and proper second harmonic separation .... I accidentally plugged in the 14 pin header, one location off, which put 12v power where it should not be.

SNAP - CRACKLE - POP

I replaced C8 and 78L05 and main unit powers up with 5v micro USB. I'm still searching the board for obvious issues but not found them yet.... I have purchased a replacement Main board and radio is operating again.
Bill - W3SI
N4XTL
 

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Re: Careless error, help diagnosing after frying it?

Post by N4XTL »

KO4NDP wrote: 29 Jul 2022, 19:47 I could not get that from digikey or mouser or adafruit, not even in a breakout board it seems? So I got a cheap INA219 breakout board off amazon. It for sure is the wrong IC package, BUT it should be deadbuggable, datasheet indicates the pins are 100% flipped. I'll confirm and do that if I've done everything else above and still don't have a power reading.
If the chip on the breakout board doesn't work, Arrow Electronics has INA219s in stock. I am getting parts together to assemble my own RF boards. I was thankful to find that chip from a US distributor, but unfortunately has to order TCA9555PWRs from a Chinese seller. Actually two different sellers, hopefully between the two orders one will show up with usable chips...

I suppose at some point we could mention that reverse polarity protection would be a nice addition to the (tr)uSDX design, especially since the kits don't come with a power cable and everyone has to make their own...
KO4NDP
 

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Joined: 25 Jul 2022, 19:15

Re: Careless error, help diagnosing after frying it?

Post by KO4NDP »

Replaced C2 and C41 to start with. With that (specifically C2) I can hook it back up to power, transmit into a dummy load, and see RF on another radio on that frequency. So it's transmitting. Power is showing 0w, 0.0% (was worse before...) so guessing that INA board needs swapping?

With C41, I can hook it up to USB, radio powers on and operates. Computer "doesn't recognize" it, but it's at least not giving a nasty power surge message.

INA next.
KO4NDP
 

Posts: 10
Joined: 25 Jul 2022, 19:15

Re: Careless error, help diagnosing after frying it?

Post by KO4NDP »

Thanks for the pointer to Arrow. $2 and change, $6 shipping, which all is the price I paid for this breakout board at amazon that I'd have to desolder this tiny guy and deadbug it since it's the wrong package. Yes please. Ordered. Wish I'd seen them earlier. They don't have the CH340G either though, only in the sparkfun board which I got at digikey, and looks like I'll have to do (maybe... optionally, if i want to ever hook it up to usb again).
KO4NDP
 

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Joined: 25 Jul 2022, 19:15

Re: Careless error, help diagnosing after frying it?

Post by KO4NDP »

Update. I swapped the CH340G with a new one, from a sparkfun serial breakout board. After that, my laptop now recognizes it and loads the COM port properly. I assume it can communicate, I didn't try flashing it, but having it not tell me it doesn't recognize the device was a win. This was a reasonably good way to go about it, the sparkfun CH340G breakout board was reasonably affordable and obtainable anywhere and the IC was easy to remove (easier than on the trusdx main board for sure).

I got the INA219 from Arrow and swapped it on the RF board. Still didn't read power properly, plugged into power supply @13.1V, transmitting CW into a dummy load (not on practice mode), tried all the bands with the same result. Reflowed the solder just in case, same. Previously I'd only replaced C2 and C41 caps (both 10uF tantalums), I went ahead and replaced C4 (also 10uF) and C8 (470 tantalum) as well, didn't seem to help, both of those were already in good shape visually, everything was powering up and running so no reason to suspect these, just wanted to eliminate doubt.

Getting the power reading correct I believe is the last fix needed. I had to stop last night, will take a closer look tonight and review the schematics and see if anything else jumps out. If anyone has ideas about what else might be a problem let me know.

Almost there
Jason KO4NDP
AC9YY
 

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Location: Illinois, USA

Re: Careless error, help diagnosing after frying it?

Post by AC9YY »

Does the power look fine, but meter just reads wrong? If so, look for the thread where a couple of resistors were added, 1 M ohm I think.
KO4NDP
 

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Re: Careless error, help diagnosing after frying it?

Post by KO4NDP »

Will check out that thread thanks.

Yes, when I first got done with initial assembly, before I screwed this up with a bad cable, I checked power and it read 6.something watts with some valid efficiency, I don't even recall the band, probably 40. I didn't bother tinkering with it yet since I knew I was about to make a new power source with a different voltage. But yeah it definitely worked prior. And it *seems* to be working now as I can see the RF in another nearby radio when transmitting into the dummy load, so the 0.0w it's showing is for sure wrong.

Appreciate it
Jason KO4NDP
AntonR
 

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Re: Careless error, help diagnosing after frying it?

Post by AntonR »

Hi Jason,

I fixed my radio! Replaced C2 and C41 with through hole capacitors and replaced the BS170 FET’s.

After replacing the two capacitors I could use USB power to start the mainboard and had already low power on transmit in display. 0,4W.

When I powered on with 12V after replacing the FET’s everything is back to normal.

73, Anton
KO4NDP
 

Posts: 10
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Re: Careless error, help diagnosing after frying it?

Post by KO4NDP »

Anton,
Same here! New transistors arrived today, just got them mounted and now I have a power and efficiency reading. Woohoo!

So to recap my issues and replacements for future folks who zap it:
- Unit powered on 12v, not on 5v and computer gave nasty message about faulty device causing power surge
- 12V Transmit appeared functional but did not give power readings
- C2 visibly blown
- C41 visibly blown

Replaced:
- C2 (https://www.digikey.com/en/products/det ... RNJ/563762)
- C41 (same as C2)
Unit then powered on with 5V but computer didn't recognize the device, CH340G COM Port not provided

Replaced:
- C4 not blown, replaced as a precaution (same as C2)
- C8 (or whatever the 470pf one is) not blown, replaced as a precaution (https://www.digikey.com/en/products/det ... RNJ/563845)
- CH340G seemed damaged, though not visible, replaced (snagged the chip off https://www.digikey.com/en/products/det ... 50/6674604)
The CH340G replacement corrected USB being able to work properly with computer, recognized device and gave COM port
Power and efficiency readings still not working

Replaced:
- INA219 seemed damaged, though not visible, replaced (https://www.arrow.com/en/products/ina21 ... INA219AIDR)
This didn't seem to have any effect, power and efficiency readings still not working

Replaced:
- BS170 MOSFETs identified as next probable, weren't blown or visibly problematic, replaced (https://www.digikey.com/en/products/det ... 170/244280)
Unit now gives power reading and efficiency.

I think it's done now but will run through stuff tomorrow and make sure everything works ok. Power is 6.something on 40m with 60something efficiency. I haven't checked the harmonic or anything else yet, will soon. But will put it on an antenna just to hear the dang thing one time and make sure all is well and move on to tuning it up.

Thanks to DL2MAN and N4XTL and several others for your help. And the schematic by KD4SGE & WA4ITD (viewtopic.php?t=513) was invaluable. And the parts list spreadsheets in the group buy page was easy enough to cross reference, the LCSC part numbers were a huge help. What an amazing project, thanks guys.

Jason KO4NDP
N4XTL
 

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Re: Careless error, help diagnosing after frying it?

Post by N4XTL »

Glad you got it working. If there's a silver lining it's that you know a heck of a lot about the radio's design now! :D
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